Wow, thanks! Yeah, I'm sure nowadays this lower may have gone the way of the Dodo, but just to know that one actually does exist somewhere is nice.

I think I'll probably just end up starting off with a standard AR-15 lower, finish off a really nice 5.56 variant, then head in the direction of an AR-10 for the power calibers. But I'll always keep my eyes peeled for the colt lower Thanks a lot to everyone!